/*
 * Copyright 2007 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*namespace com.google.zxing.qrcode.decoder {*/

import ErrorCorrectionLevel from './ErrorCorrectionLevel'
import Integer from './../../util/Integer'

/**
 * <p>Encapsulates a QR Code's format information, including the data mask used and
 * error correction level.</p>
 *
 * @author Sean Owen
 * @see DataMask
 * @see ErrorCorrectionLevel
 */
export default class FormatInformation {

  private static FORMAT_INFO_MASK_QR = 0x5412

  /**
   * See ISO 18004:2006, Annex C, Table C.1
   */
  private static FORMAT_INFO_DECODE_LOOKUP = [
      Int32Array.from([0x5412, 0x00]),
      Int32Array.from([0x5125, 0x01]),
      Int32Array.from([0x5E7C, 0x02]),
      Int32Array.from([0x5B4B, 0x03]),
      Int32Array.from([0x45F9, 0x04]),
      Int32Array.from([0x40CE, 0x05]),
      Int32Array.from([0x4F97, 0x06]),
      Int32Array.from([0x4AA0, 0x07]),
      Int32Array.from([0x77C4, 0x08]),
      Int32Array.from([0x72F3, 0x09]),
      Int32Array.from([0x7DAA, 0x0A]),
      Int32Array.from([0x789D, 0x0B]),
      Int32Array.from([0x662F, 0x0C]),
      Int32Array.from([0x6318, 0x0D]),
      Int32Array.from([0x6C41, 0x0E]),
      Int32Array.from([0x6976, 0x0F]),
      Int32Array.from([0x1689, 0x10]),
      Int32Array.from([0x13BE, 0x11]),
      Int32Array.from([0x1CE7, 0x12]),
      Int32Array.from([0x19D0, 0x13]),
      Int32Array.from([0x0762, 0x14]),
      Int32Array.from([0x0255, 0x15]),
      Int32Array.from([0x0D0C, 0x16]),
      Int32Array.from([0x083B, 0x17]),
      Int32Array.from([0x355F, 0x18]),
      Int32Array.from([0x3068, 0x19]),
      Int32Array.from([0x3F31, 0x1A]),
      Int32Array.from([0x3A06, 0x1B]),
      Int32Array.from([0x24B4, 0x1C]),
      Int32Array.from([0x2183, 0x1D]),
      Int32Array.from([0x2EDA, 0x1E]),
      Int32Array.from([0x2BED, 0x1F]),
  ]

  private errorCorrectionLevel: ErrorCorrectionLevel
  private dataMask: number/*byte*/

  private constructor(formatInfo: number /*int*/) {
    // Bits 3,4
    this.errorCorrectionLevel = ErrorCorrectionLevel.forBits((formatInfo >> 3) & 0x03)
    // Bottom 3 bits
    this.dataMask = /*(byte) */(formatInfo & 0x07)
  }

  public static numBitsDiffering(a: number /*int*/, b: number /*int*/): number /*int*/ {
    return Integer.bitCount(a ^ b)
  }

  /**
   * @param maskedFormatInfo1 format info indicator, with mask still applied
   * @param maskedFormatInfo2 second copy of same info; both are checked at the same time
   *  to establish best match
   * @return information about the format it specifies, or {@code null}
   *  if doesn't seem to match any known pattern
   */
  public static decodeFormatInformation(maskedFormatInfo1: number /*int*/, maskedFormatInfo2: number /*int*/): FormatInformation {
    const formatInfo = FormatInformation.doDecodeFormatInformation(maskedFormatInfo1, maskedFormatInfo2)
    if (formatInfo !== null) {
      return formatInfo
    }
    // Should return null, but, some QR codes apparently
    // do not mask this info. Try again by actually masking the pattern
    // first
    return FormatInformation.doDecodeFormatInformation(maskedFormatInfo1 ^ FormatInformation.FORMAT_INFO_MASK_QR,
      maskedFormatInfo2 ^ FormatInformation.FORMAT_INFO_MASK_QR)
  }

  private static doDecodeFormatInformation(maskedFormatInfo1: number /*int*/, maskedFormatInfo2: number /*int*/): FormatInformation {
    // Find the int in FORMAT_INFO_DECODE_LOOKUP with fewest bits differing
    let bestDifference = Number.MAX_SAFE_INTEGER
    let bestFormatInfo = 0
    for (const decodeInfo of FormatInformation.FORMAT_INFO_DECODE_LOOKUP) {
      const targetInfo = decodeInfo[0]
      if (targetInfo === maskedFormatInfo1 || targetInfo === maskedFormatInfo2) {
        // Found an exact match
        return new FormatInformation(decodeInfo[1])
      }
      let bitsDifference = FormatInformation.numBitsDiffering(maskedFormatInfo1, targetInfo)
      if (bitsDifference < bestDifference) {
        bestFormatInfo = decodeInfo[1]
        bestDifference = bitsDifference
      }
      if (maskedFormatInfo1 != maskedFormatInfo2) {
        // also try the other option
        bitsDifference = FormatInformation.numBitsDiffering(maskedFormatInfo2, targetInfo)
        if (bitsDifference < bestDifference) {
          bestFormatInfo = decodeInfo[1]
          bestDifference = bitsDifference
        }
      }
    }
    // Hamming distance of the 32 masked codes is 7, by construction, so <= 3 bits
    // differing means we found a match
    if (bestDifference <= 3) {
      return new FormatInformation(bestFormatInfo)
    }
    return null
  }

  public getErrorCorrectionLevel(): ErrorCorrectionLevel {
    return this.errorCorrectionLevel
  }

  public getDataMask(): number/*byte*/ {
    return this.dataMask
  }

  /*@Override*/
  public hashCode(): number /*int*/ {
    return (this.errorCorrectionLevel.getBits() << 3) | this.dataMask
  }

  /*@Override*/
  public equals(o: Object): boolean {
    if (!(o instanceof FormatInformation)) {
      return false
    }
    const other = <FormatInformation> o
    return this.errorCorrectionLevel === other.errorCorrectionLevel &&
        this.dataMask === other.dataMask
  }

}
